Radio frequency (RF) signals propagate through the air predictably. However, when physical structures are present, such structures may absorb or reflect the RF signals. In these situations, signal degradation or multipath issues may occur (multipath is generally described as an RF signal reaching an antenna over two or more distinct paths).
U.S. Pat. No. 8,749,433, granted Jun. 10, 2014, titled “Multiplexing Receiver System”, the entirety of which is incorporated by reference herein, discloses a system for tracking mobile RF transmitters, wherein RF receivers receive RF signals transmitted from a mobile RF transmitter. Based on the phase of the RF signal as received at multiple receiver antennae, the distance between the receiver antennae and the transmitter is calculated along a line. With multiple appropriately spaced antennae, the location of the RF transmitter can be calculated and the position of the mobile RF transmitter may be tracked.
In such a system, while the data sent in the RF signal is important, the integrity of receiving the correct signal is imperative. Thus, if an object (a person) is disposed between the RF transmitter and an antenna and impedes the signal, the transmitter cannot be tracked as the signal may not be received. Also, the signal being utilized to track the transmitter must be the “straight line” signal from the transmitter and not a multipath signal as created by signal reflection from a surface.